Billy Bob Thornton stars as Secret Service Agent Forrest Sorrels in 'Parkland,' written and directed by Peter Landesman. The look at the Kennedy assassination is due out Sept. 20, near the 50-year anniversary of the fateful day -- Nov. 22, 1963 -- when President Kennedy was killed in Dallas. The film looks at the vital, smaller characters swept up in the terrible drama, including Sorrels, a true professional. "He was all business," says Thornton. "And that's the way I played him." Claire Folger, Exclusive Media Entertainment

Marcia Gay Harden stars as the head nurse of the trauma unit at Dallas' Parkland Hospital, where the critically wounded president was taken. Zac Efron plays a rookie doctor, the only doctor on duty at the time. “One of the greatest things about Parkland is that a few ordinary men were placed under extraordinary circumstances," says Efron. "It's amazing to witness people defy the odds in the face of chaos.” Claire Folger, Exclusive Media Entertainment

Paul Giamatti plays Abraham Zapruder, who happened to be filming the president's motorcade when mayhem broke out. The resulting video is "the most examined and investigated pieces of celluloid in the history of film," says Landesman. The director said Giamatti had "a surreal" moment playing out this historic moment on location at Dallas' Dealey Plaza. Claire Folger, Exclusive Media Entertainment

The hospital scenes for Parkland were shot in an Austin hospital that was a "dead ringer" for Parkland Memorial Hospital, says Landesman. Here, Efron's doctor deals with watching two critically wounded patients die in the span of two days -- President John F. Kennedy and his assassin Lee Harvey Oswald. "At this point he cannot believe he has lost them both," says Landesman. Claire Folger, Exclusive Media Entertainment